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I ordered SMD 0805 components among other items and I received a package with the SMD components but there is no description at all.

Also, there is no identification on the components itself.

Is there an easy way to find out if the components I have are ferrite beads? (that's the most logical type I can expect from the post).

When I used a DMM to measure the resistance it is 0 ohm, which seems normal for ferrite beads.

(note I don't have any EMI test, but I have an (old) oscilloscope if needed).

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    \$\begingroup\$ Does your scope have a test (square wave) output for probe adjustment? \$\endgroup\$ Jul 30, 2019 at 9:54
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    \$\begingroup\$ Reputable supplier of electronic components or ebay? \$\endgroup\$
    – Andy aka
    Jul 30, 2019 at 10:01
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    \$\begingroup\$ No further comment! \$\endgroup\$
    – Andy aka
    Jul 30, 2019 at 10:40
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    \$\begingroup\$ "White" sounds less like a ferrite (or even an inductor) and more like a resistor. \$\endgroup\$
    – JRE
    Jul 30, 2019 at 10:47
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    \$\begingroup\$ If they drop on the floor and there's a mixture of parts and those parts are not uniquely marked then I would put them in the trash unless they were high value parts. More than likely they would end up in the trash with a note to myself not to be so careless. \$\endgroup\$
    – Andy aka
    Jul 30, 2019 at 11:04

2 Answers 2

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If your oscilloscope has a calibration output (to calibrate probes), you could use that signal (after having calibrated the probes!) to check with the frequency characteristics of the ferrite beads.

enter image description here Source: https://learn.sparkfun.com/tutorials/how-to-use-an-oscilloscope/all

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  • \$\begingroup\$ To be honest, I don't know if mine has, I will check, thanks for the picture and link. \$\endgroup\$ Jul 30, 2019 at 10:20
  • \$\begingroup\$ Note the test signal is probably 1kHz and the bead is probably active at 100MHz so the effect will be tiny. This might help. \$\endgroup\$
    – rdtsc
    Jul 30, 2019 at 13:51
  • \$\begingroup\$ @rdtsc You should of course zoom in at the transients in this 1kHz signal \$\endgroup\$
    – Huisman
    Jul 30, 2019 at 13:59
  • \$\begingroup\$ I hope my scope is that accurate (it's a very old Philips PM3110, I also have a PM 3253 but that one is barely usable). I will accept the answer because it seems the good way to test (but the test itself has to wait until I have some more time). \$\endgroup\$ Jul 30, 2019 at 21:13
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A ferrite bead will measure close to zero ohms and will be strongly attracted to a permanent magnet.

If you have a spectrum analyzer with tracking generator, or at least a signal generator and oscilloscope, you can get an idea of the impedance (often measured at 100MHz).

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  • \$\begingroup\$ I will try the magnet 'test' (that one is easy) and do the test as Huisman specifies (seems similar as your proposal) \$\endgroup\$ Jul 30, 2019 at 13:14
  • \$\begingroup\$ Upvoted, although I also tried a resistor and that is also attracted strongly, the other tip with the oscilloscope I will try when I have some more time. \$\endgroup\$ Jul 30, 2019 at 21:14

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